Cooking pots and pans can, under many circumstances, suffer from a phenomenon called “boil over.” Boil over occurs when the contents of the cooking pot expand and force the contents over the rim of the cooking pot. This can be caused by many different mechanisms, including when the food being cooked gives off sugars, starches, or proteins, or otherwise becomes viscous, thereby increasing the surface tension of the contents of the cooking pot so that the steam bubbles formed during boiling do not burst. Instead, the steam bubbles build upon one another and cause rapid expansion of the contents of the cooking pot. The result is that the contents are forced from the cooking pot or pan and spill outward, often onto the cooking surface. The spillage can burn, thereby creating smoke and a burnt odor and, in more severe cases, a burn hazard to the cook and a risk of fire.
Boil over is usually controlled by cooking without a lid on the cooking pot or pan. This allows steam to escape from the cooking pot or pan and can, in certain circumstances, prevent boil over. However, in some circumstances, only constant stirring prevents or limits boil over. This is probably a familiar situation for many cooks who must constantly stir a pot of potatoes, pasta, gravy, sauce, or caramel to prevent boil over caused by the accumulation of starches or proteins, or other causes of increased viscosity, at the liquid surface. The drawbacks, aside from the inconvenience of constant stirring, are that constant stirring can extend cooking time by cooling the food and can break up certain foods, such as potatoes, thereby inadvertently altering the texture of the food.
Various pans with lids have been developed over the years toward resolving this boil over issue. Representative examples of prior art pans with lids are disclosed in U.S. Pat. No. 504,243 to Philippot, U.S. Pat. No. 1,461,366 to Mulford et al., U.S. Pat. No. 1,676,146 to Kraft, U.S. Pat. No. 1,810,860 to Tremblay, U.S. Pat. No 2,127,988 to Tarrant, U.S. Pat. No. 2,385,594 to Witte, Jr., U.S. Pat. No. 5,193,524 to Loyd et al., hereby incorporated by reference. However none of these prior at lids provide a comprehensive solution to preventing boiling over while maintaining cooking efficiencies including flavor and food texture. Namely, the lids allow for the escape of steam to reduce the boiling over effect, but at the same time results in a lengthening of the cooking time due to the escape of the steam. Also, during the cooking process flavor is lost and food texture compromised as a result of the loss of steam.
Turning to U.S. Pat. No. 5,033,453 which is hereby incorporated by reference shows an overflow cooking pot assembly. The assembly includes a main support pan member; an intermediate lid member; and a main outer lid member. The main support pan member is provided with a main support section integral with a fluid overflow section extending laterally and upwardly therefrom. The intermediate lid member is provided with vent slots to permit overheated fluid or food product to move into the fluid overflow section for cooling thereof One use of the basic cooking pot assembly is illustrated whereupon both the intermediate lid member and the main outer lid member can be mounted on the main support pan member for a steaming and cooking operation. This cooking pot assembly while addressing overflow is cumbersome requiring multiple lids and is not designed to provide maximum cooking efficiencies.
U.S. Pat. No. 6,125,842 discloses an overflow pan assembly with a splashguard cap and cap positioning means. The plate or lid has a series of holes or apertures on the top with a cover secured over the holes. The cover is freely moveable in an axial direction when pressure is exerted upwards upon it. Until the water or broth is heated up to a boil, the holes are closed capturing the steam within the pot. When the broth is boiled, the cover is shifted upward by the steam opening the holes for the boiled broth to discharge, pass along the plate or lid and back into the pot. Again, while this invention addresses the boil over spillage and maintains the steam in the pot, it only does so until the broth is boiled. The problem here is cooking of the food takes place for the most part after boiling and the steam is released already resulting in an inefficient cooking pot.
Thus, it can be seen that there is a need in the art for a faster cooking container that cooks combining the efficiencies of steam and boiling in a controlled manner such that food taste and texture is preserved. The container of the invention also reduces the likelihood that boil over will occur and, if the phenomenon does occur, ensures that the contents are contained, rather than spilling from the cooking container.